Seaplane



July 16, 1929.

L. STAIGER SEAPLANE Filed Feb- 12, 1927 Fig. 1

Patented July 16, 1929.

1,720,698 PATENT OFFICE.

LUDWIG STAIGER, F BIRKENWERDER. NEAR BERLIN, GERMANY, A SSIGNOR TO THE FIRM: ROHRBACH METALL-FLUGZEUGBAU G. M. B. H., OF BERLIN, GERMANY.

SEAPLAN E.

Application filed February 12, 1927, Serial No. 167,644, and in Germany February 15, 1926.

This invention relates to seaplanes. Seaplanes provided with central stabilizing and floating devices are capable of retaining their stability in a not too agitated sea, such stabilizing devices including, for instance, in the case of float-machines, two main floats, in the case of flying-boats, boathull and either lateral sponsons or supporting floats, arranged nearly adjacent to the hull. It has however, been proved to be desirable to so design said machines, that they are able to withstand even heavier seas, i. e., to increase their floating stability with regard to the occurring greater stresses. It is understood that an improvement in this respect should never be obtained at the price of, for instance, poorer flying properties, or other drawbacks of any kind.

The invent-ion results in a happy solution of above problem, and resides in the provision of, in addition to the central floating and stabilizing devices, auxiliary floats att-ached to the supporting planes proper and arranged direct-1y inside the supporting wing, i. e., inside its free ends, said auxiliary floats preferably being composed of a hollow-box shaped wing with watertight compartments subdivided by bulkheads.

Being provided with a float arrangement according to the invention, seaplanes of the discussed type are capable of withstanding rather heavy seas and returning to their normal floating. position without any difliculty, in case one of the wings is forced down onto the water. Another remarkable feature of the invention is, that the floats which are incorporated in the wing tips can be used as safety devices, steadying the machine in case so emergency, if parts of the central stabilizing devices, sponsons or supporting floats for instance, should spring leaks. This particularly applies to wings designed to be floatable over their whole or nearly their whole length. Moreover the auxiliary floats can be used for controlling purposes, when the machine is abruptly veering round in the open sea, by intentlonally immersing, the wing tips, thus causing the airplane to describe a more or less circular curve pivoting about the said wing tip.

It is a well known practice, in the case of unstably floatin seaplanes, to arrange wing tip floats at a httle distance below the free ends of the supporting planes, protecting the alternatively down-forced wings from being completely immersed. Said wing tip floats are of course dispensed with in the case of aircraft of the above described type, with regard to the central floating stabili zation. Owing to their position in the free wind, they produce an increase of flying resistance, thus impairing the air flow round the wings. It has been proposed, in this connection, to so design the free ends of the bottom surface of an unstably floating biplane flying-boat, that they can be used as wing tip floats and ailerons as well; in practice however, this form of construction means a failure, since the lifting forces of the wing tip floats must be absorbed by the aileron ropes. v

Several embodiments of the invention are shown, by way of example, on the accompanying drawing, wherein Figs. 1 and 2 represent a monoplane, reposing on -the water in a horizontal and a considerably inclined position. Figs. 3 and 4 show two forms of wing sections, on an enlarged scale.

A seaplane designed as. flying-boat, according to Figs. 1 and 2 provides two stabilizing floats 6, arranged laterally and in close proximity to the hull, said floats working, with the machine being at rest, as statical lifting members, and, with the machine taking off, as dynamical lifting members. In the free ends of the supporting wings c floating members or parts (Z are provided, which, owing to the considerable distance between them and the vertical central plane of the machine, produce a rather great lifting moment, notwithstanding their relatively small size. The floating parts are observed to extend a considerable distance from the wing tips toward the wing roots.

In case of metal hollow box wings, the wing tips are designed as watertight floatable compartments. Fig. 3 is a schematic cross Section through a wing of the above type. 0 are vertical supporting spars, rigidly lnterconnected at certain intervals by solid transverse bulkheads f (Fig. 1). 9 indicates the stressed outer skins, forming subdivided floatable compartments in conjunction with the walls f and spars e.

The wing according to Fig. 3 is threepartite. Nose edge i and rear edge 7' are detachabl hinged to the central wing part, which 1s attached to the air craft fuselage or flying boat hull resp., said nose and rear edges being allowed to be designed either separately or jointly as floating bodies, and suitably providing a subdivision corresponding towing compartments, in the wing span direction.

When the edge parts i, j are detached or Unhinged, the spar inside parts e serve as coverings for the spar holes, which are meant to facilitate the making or backing up of rivets, during the construction of the wing box girder. n is a drain screw.

Fig. 4 represents a box wing, made of whatever material, to be floatable by providing, inside the girder compartments, an inflatable, watertight tank a, a rubber pocket, for instance, which is tightly filled with air or the like. 71. indicates the pump connection.

It may occur, under certain conditions, that the section height of thefloating body is of larger size than that of the wing. One then provides it with a supporting plane section, in order to avoid (llStl.ll'l)21.l1C(3 of air flow. Fig. 2 shows, in dotted lines, such a body 0, which prevents the spilling of the air flow over the wing tip.

It is of no consequence whether the machine be a monoplane or multiplane or whether the floating members are provided to be situated in close proximity of the aircraft centre. There are circumstances, where it shall be advisable to design the Whole wing as floatable structure, subdividing same into compartments by means of bulkheads, or to arrange the floating members over the whole length of the wing. Providing a non-floatable gutter edge at the wing tip, has no hearing upon the present invention.

What I claim is:

1. In a seaplane, the combination of a central floating system including two displacement floats located in proximity to, but on Opposite sides of, the vertical plane passing through the central longitudinal axis of the craft and adapted to be simultaneously immersed when the craft is floating, an air lift or supporting wing carried by the floats and normally disposed above the water line throughout its length, and floating means located immediately at or in proximity to the free ends of said supporting wing and incorporated therein as a part thereof.

2. In a seaplane of the character set forth in claim 1 wherein the central floating system includes as a third float a. boat structure lying between the two centrally disposed dis placement floats and functioning with them to support and float the craft.

3. In a seaplane of the character set forth in claim 1 wherein the floating means which forms a part of the wing extends from the free ends thereof to its root.

4. In 'a seaplane the combination of a central floating system including two displacement floats disposed in proximity to, but on opposite sides of the vertical plane through the longitudinal axis of the craft and adapted to be simultaneously immersed when the craft is floating, an air lift or supporting wing carried by-said floats and normally disposed above the water line throughout its length, said supporting wing including buoyant compartn'ients incorporated in the free end tips thereof and said con'ipartments being subdivided by bulkheads.

5. In a seaplane, the combination of a central floating system including at least two displam-ment floats arranged near the center thereof, with a supporting wing arranged above the central floating system, said sup porting wing including a central supporting part having floatable or buoyant end portions and detachable nose and tail parts.

6. A seaplane of the character set forth in claim 5 wherein the central Wing supporting part is of all metal with the floatable part a hollow body formed by water-tight connections and including lateral frame members which are provided with apertures leading to the hollow body, together with means for closing said apertures.

7. In a seaplane of the character set forth in claim 5 wherein the floatable part of the central wing structure includes an one allmetal piece forming a hollow body and is subdivided by means of bulkheads into a number of water-tight compartments, the lateral frame members of the floatable central part of the wing being provided with apertures which lead to the compartments, together with means for closing said apertures.

8. In a seaplane of the character set forth in claim 5 wherein the central floating system includes a boat hull disposed between the two lateral floats.

9. In a seaplane of the character set forth in claim 1 wherein the auxiliary floating means is formed into a supporting surface section which is of greater depth at that point than the wing.

10. In a seaplane, the combination of a central floating system, including a boat hull and two lateral displacement floats in close proximity to the boat hull, the said three floating bodies adapted to support and stabilize the craft when floating in the water, a supporting wing arranged above the central floating system, said supporting wing including central metal supporting part and having floatable or buoyant end compartments and detachable nose and tail parts, the floatable part of the central wing structure consisting of an all-metal piece forming a hollow body and being subdivided by means of bulkheads into a number of water-tight compartments, the lateral frame members of the floatable central part of the wing being provided with apertures which lead to the compartments, together with means for closing said apertures.

11. A seaplane of the character set forth in claim 10 wherein the central supporting part of the wing contains water-tight compartments throughout its entire length.

12. A seaplane of the character set forth in claim 10 wherein at least some of the detachable nose and tail parts of the wing are formed as floatable or buoyant bodies.

13. A seaplane of the character set forth in claim 10 of the monoplane type with the wing halves spreading widely relative to the central floating system.

14. In a seaplane of the monoplane type, the combination of a central floating system including at least two displacement floats located in the region of the vertical plane passing through the central longitudinal axis ofthe craft and adapted to be simultaneously immersed when the craft is floating, a monoplane wing carried by the floats and normall disposed above the water line throughout its length, and floating means located directly on the free ends of said supporting wing and incorporated therein as a part thereof, said floating means extending over a large portion of the wing span towards the wing root.

In testimony whereof, I have signed my name to this specification.

LUDWIG STAIGER. 

